package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CaheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CaheClient caheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透
        Shop shop = caheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //互斥锁缓存击穿
        //Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
//        Shop shop = caheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, LOCK_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.SECONDS);

        if(shop == null)
            return Result.fail("店铺不存在！");

        return Result.ok(shop);
    }

//    public Shop queryWithMutex(Long id) {
//        String key = CACHE_SHOP_KEY + id;
//
//        // 1. 从redis查缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//
//        // 2. 判断是否存在（非空且非空字符串）
//        if (StrUtil.isNotBlank(shopJson)) {
//            return JSONUtil.toBean(shopJson, Shop.class);
//        }
//
//        Shop shop = null;
//        // 自旋重试次数限制（避免无限循环）
//        int maxRetryCount = 10;
//        int retryCount = 0;
//
//        String lockKey = LOCK_SHOP_KEY + id;
//
//        try {
//            // 4. 不存在，自旋获取锁, 避免栈溢出
//            while (!tryLock(lockKey)) {
//                // 超过最大重试次数，返回null或抛出异常
//                if (retryCount >= maxRetryCount) {
//                    return null; // 或 throw new RuntimeException("获取锁失败");
//                }
//                // 休眠后重试
//                Thread.sleep(50);
//                retryCount++;
//            }
//
//            // 获取到锁后，再次检查缓存（双重校验，避免重复查库）
//            shopJson = stringRedisTemplate.opsForValue().get(key);
//            if (StrUtil.isNotBlank(shopJson)) {
//                return JSONUtil.toBean(shopJson, Shop.class);
//            }
//
//            // 查数据库
//            shop = getById(id);
////            //模拟重建延时
////            Thread.sleep(200);
//            if (shop == null) {
//                // 缓存空值，防止缓存穿透
//                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
//                return null;
//            }
//
//            // 写入缓存
//            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        } catch (InterruptedException e) {
//            throw new RuntimeException(e);
//        } finally {
//            // 释放锁
//            unlock(lockKey);
//        }
//
//        return shop;
//    }

//    //缓存穿透
//    public Shop queryWithPassThrough(Long id){
//        String key = CACHE_SHOP_KEY + id;
//
//        //1.从redis查缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//
//        //2.判断是否存在
//        if (StrUtil.isNotBlank(shopJson)) {
//            //3.存在，直接返回
//            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
//            return shop;
//        }
//
//        if (shopJson != null){
//            return null;
//        }
//
//        //4.不存在，根据id查数据库
//        Shop shop = getById(id);
//
//        //5.不存在，返回错误
//        if (shop == null) {
//            //将空值写入redis，防止缓存穿透
//            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
//
//            return null;
//        }
//
//        //6.存在，先写入redis，再返回
//        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
//
//        return shop;
//    }

//    //线程池
//    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
//
//    public Shop queryWithLogicalExpire(Long id){
//        String key = CACHE_SHOP_KEY + id;
//
//        //1.从redis查缓存
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//
//        //2.判断是否存在
//        if (StrUtil.isBlank(shopJson)) {
//            //3.不存在，直接返回
//            return null;
//        }
//
//        //4，判断缓存是否过期
//        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
//        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
//        LocalDateTime expireTime = redisData.getExpireTime();
//
//        //未过期，直接返回
//        if(expireTime.isAfter(LocalDateTime.now())){
//            return shop;
//        }
//
//        //5.缓存过期，尝试获取锁
//        String lockKey = LOCK_SHOP_KEY + id;
//        boolean isLock = tryLock(lockKey);
//
//        //6.获取到锁，开启独立线程并最终释放互斥锁
//        if(isLock){
//            CACHE_REBUILD_EXECUTOR.submit(()->{
//                try {
//                    this.saveShop2Redis(id,20L);
//                } catch (Exception e) {
//                    throw new RuntimeException(e);
//                } finally {
//                    unlock(lockKey);
//                }
//            });
//
//        }
//
//        return shop;
//    }
//
//    //获取锁
//    private boolean tryLock(String key){
//        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 1, TimeUnit.SECONDS);
//        return BooleanUtil.isTrue(flag);
//    }
//
//    //释放锁
//    private void unlock(String key){
//        stringRedisTemplate.delete(key);
//    }


    @Override
    @Transactional
    public Result update(Shop shop) {
        if(shop.getId() == null){
            return Result.fail("店铺id不能为空");
        }

        //1.更新数据库
        updateById(shop);

        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());

        return Result.ok();
    }

    @Override
    public Result queryByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要坐标进行查询
        if(x == null || y == null){
            //1.1.原始查询逻辑并分页
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }

        //2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        //3.查询redis，结果：shopId , distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
                key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end));

        if(results == null)
            return Result.ok(Collections.emptyList());

        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();

        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> distanceMap = new HashMap<>(list.size());

        if(list.size() <= from){
            //没有下一页，直接结束
            return Result.ok(Collections.emptyList());
        }

        list.stream().skip(from).forEach(res -> {
            //获取店铺id
            String shopId = res.getContent().getName();
            ids.add(Long.valueOf(shopId));
            //获取距离
            Distance distance = res.getDistance();
            distanceMap.put(shopId,distance);
        });

        //4.解析id并查询店铺信息，封装
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }

        //4.返回结果
        return Result.ok(shops);

    }


    //预先添加热点数据进缓存
    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);

        //2，封装为逻辑过期
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));

        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));

    }


}
